DOCSLIB.ORG

PRESBYOND Laser Blended Vision Practical Guide

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
PRESBYOND Laser Blended Vision Practical Guide PRESBYOND Laser Blended Vision Practical Guide Disclaimer: This practical guide was produced independently by Dan Z Reinstein, MD MA(Cantab) FRCSC DABO FRCOphth FEBO1, 2, 3, 4 Glenn I Carp, MBBCh, FC Ophth (SA)1 Timothy J Archer, MA(Oxon), DipCompSci(Cantab)1, 4 Sharon Ritchie, BSc (Hons), MCOptom1 1 London Vision Clinic, London, UK 2 Department of Ophthalmology, Columbia University Medical Center, NY, USA 3 Centre Hospitalier National d’Ophtalmologie, Paris, France 4 Biomedical Science Research Institute, University of Ulster, Coleraine, Northern Ireland Financial Disclosure: Dr Reinstein is a consultant for Carl Zeiss Meditec (Carl Zeiss Meditec AG, Jena, Germany) and has a proprietary interest in the Artemis technology (ArcScan Inc, Golden, Colorado) through patents administered by the Center for Technology Licensing at Cornell University (CTL), Ithaca, New York. Dr Carp receives travel expenses from Carl Zeiss Meditec. The remaining authors have no proprietary or financial interest in the materials presented herein. Preoperative 1. Pre-operative testing protocol 2. Manifest refraction 3. Dominance testing 4. Laser Blended Vision tolerance assessment 5. What myopic target to expect 6. Laser Blended Vision explanation and patient counselling Postoperative 7. Postoperative evaluation 8. Postoperative visual course 9. Cross-blur management at final outcome 10. Appendix A – Preoperative tolerance test examples 11. Appendix B – Postoperative cross-blur and enhancement examples 2 1. Pre-operative testing protocol Highlighted topics are particularly relevant for PRESBYOND • History. Motivation for surgery, previous ocular • Cirrus OCT corneal and epithelial pachymetry. history (including detailed history of contact lens wear, • Undilated WASCA aberrometry. period of wear, type of lens, wear modality, last worn, • Ocular Response Analyser. comfort or visual symptoms associated with wear), family • CDVA and DCNV with WASCA sphero/cyl refraction. ocular history, detailed medical history, general health, • Manifest distance refraction (measured as standard medications, allergies, previous refractions, night vision at 6m) and CDVA and DCNV. symptoms with spectacles and/or contact lenses. Ocular • Laser Blended Vision tolerance test to find optimal symptoms, especially dry eye symptoms with/without anisometropia. contact lenses and pattern, photophobia. • Monocular distance visual acuity with +1.50 D blur • Ocular dominance by four methods: preferred sighting (for presbyopic patients). of a camera using a disposable camera as a prop, shooting • Mesopic contrast sensitivity testing (Vector Vision CSV simulation, view-finder hole test, and pointing. 1000). • Pupil reactions (PERRLA and presence or not of APD). • Slit Lamp examination. • Ocular motility testing. • TBUT. • Confrontational fields testing. • Schirmer 1b testing. • Cover testing at distance and near, with and without • Goldmann tonometry. glasses. • Cycloplegic refraction & CDVA (after instillation of • Monocular and binocular distance UCVA (using the 1.0% Tropicamide). Vector Vision CSV 1000 log MAR chart with internally • Dilated WASCA aberrometry (minimum pupil diameter regulated background illumination to ensure the contrast 6.0 mm). is the same irrespective of the room lighting). • Dilated fundus examination using both head-mounted • Monocular and binocular near UCVA. BIO and Superfield/78D lens. • Monocular and binocular intermediate UCVA. • Night vision simulation if required. • Lensometry of current spectacles and CDVA and • Night vision questionnaire (QoV validated questionnaire). DCNV with this refraction. • OSDI dry eye questionnaire. • Procyon dynamic bilateral IR pupillometry measured • KC Screening assessment considering objective tests at three different light levels: dark (0.0 Lux), scotopic and patient history. (0.04 Lux), mesopic low (0.4 Lux). • Insight Very High Frequency Digital Ultrasound • Pentacam tomography (or tomography equivalent). (if required). • Atlas topography. 3 2. Manifest refraction The goal of manifest refraction in refractive surgery is to determine the optimal sphere and cylinder lenses that will maximise visual acuity for a particular eye. Refraction for glasses is often considered to be an art, whereas refraction for surgery should be considered to science. When refracting for spectacles, the artistic elements include pushing axes to the horizontal, minimising the cylinder used, and keeping cylinder axis between the eyes orthogonal, etc. Refraction for refractive surgery is quite different in that for example we attempt to maximise cylinder and determine the exact axis of astigmatism irrespective of verticality and orthogonality to the opposite eye. Below are the flow charts that describe the manifest refraction protocol (Figure 1) and binocular balance protocol (Figure 2) that we routinely use. With this technique, we have demonstrated between observer reproducibility equivalent to within observer repeatability, in the order of 0.25 D.1 Monocular Manifest Refraction Protocol START: Initial dilated aberrometry Rx Put up 20/40 line Check visual acuity Put up Jackson Cross Put up smallest line No Add +0.25 DS Cyl = 0 Cyl < 0 No Add +0.25 DS Does this blur Test 4 positions Does this blur them a little? them a little? of axis Refine axis Yes Yes Put in -0.25 DC Refine power Remove the added +0.25 Remove the added +0.25 If >0.25 D change, refine axis Add -0.25 DS Yes Add -0.25 DS Remove Jackson Cross Can you read more letters? Can you read more letters? No Clear preference for power? No Yes No Find smallest line Yes Remove the END Remove the added -0.25 Test 0.25 DC difference added -0.25 Figure 1: Flow chart describing our monocular manifest refraction protocol. 4 Binocular Balance Protocol Add +1.50 DS lenses into both eyes* If sphere changed in one eye, remove +1.50 DS lens and check CDVA Put up 20/200 line and ask how far down the chart the patient can read Put up smallest line If can read better than 20/63 they are under- Add +0.25 D binocularly No plussed, so add plus binoculary until blurred Does this blur them a little (wait 5 secs)? Cover R and L eye alternately with your hand Both eyes see and ask which is better (sharpness not brightness) Yes the same using the 20/200 line Remove the added +0.25 One eye sees better than the other Final Binocular Rx Add +0,25 DS to eye seeing better *N.B. This is for a testing distance of 2.40 m using the CSV-1000 chart – equivalent to +1.08 D Figure 2: Flow chart describing our binocular balance protocol. 3. Dominance testing Eye dominance is recognized as a very important factor in monovision success and is based on the hypothesis that the non- dominant eye would be more easily suppressed for distance when vision is blurred than the dominant eye. We routinely evaluate the ocular dominance using four methods: the ‘hole test’, pointing, a disposable camera, and shooting a rifle. We also record the handedness of the patient. 1. The ‘hole test’ involves the patient binocularly aligning a distant object through a 1” diameter hole in a white A4 sheet of paper, held at arm’s length in landscape format with each hand holding either end. The eyes are alternately covered while looking through the hole. The eye with which the object appears most centered through the hole is deemed to be the dominant eye. 2. Pointing involves the patient pointing at a spot light source 6 meters from the patient so that their finger and the light source are visually aligned. Each eye is then occluded and the eye with the least separation between their finger and the spot is deemed to be the dominant eye. 3. A disposable camera is given to the patient and they are asked to pretend to take a photograph. The eye used to align the camera is deemed to be the dominant eye. 4. The patient is asked to pretend to shoot a rifle and the eye the patient keeps open to sight the rifle is deemed to be the dominant eye. 5 4. Laser Blended Vision tolerance assessment The standard micro-monovision protocol would correct the dominant eye to plano and the non-dominant eye to -1.50 D irrespective of age. Patients should be tested for tolerance with these refractions, with tolerance evaluated as the amount of cross-blurring reported by the patient during simulation of the intended postoperative refraction using a phoropter. Cross-blurring is a term used to describe a lack or reduction of interocular blur suppression. After first completing a full manifest refraction in both eyes, the micro-monovision assessment is performed as outlined below 1. The examiner stands in front of the patient to block his/her view of the visual acuity chart while concurrently setting the ‘R’ (retinoscopy +1.50 D) lens into the non-dominant eye. 2. The examiner then moves to the side of the patient allowing him/her to once again view the chart. 3. After a few seconds, the examiner asks the patient “how does that look?” 4. If the patient responds that everything looks fine, the examiner then asks “nothing strange?” and “no ghosting?” 5. The examiner asks the patient to read the smallest letters he/she can see at distance. 6. Next, the near chart is brought in front of the patient at 40 cm and the patient is asked to read the smallest print that is comfortable to read. 7. The examiner uncovers the distance chart again and asks the patient to read the smallest print he/she can. When removing the near chart, this should be done slowly and in such a way to uncover the distance eye first to allow the brain a chance to adapt. 8. At this point, the examiner covers the dominant eye while saying to the patient “were you at all aware of the fact that [examiner covers the dominant eye] this eye [the non-dominant eye] was very blurred at distance?” 9. If the patient states that he/she was completely unaware of this, the patient is deemed to be tolerant of a +1.50 D ‘add’.
Load more

Recommended publications
  • Hyperopia Hyperopia
    Hyperopia Hyperopia hyperopia hyperopia • Farsightedness, or hyperopia, • Farsightedness occurs if your eyeball is too as it is medically termed, is a short or the cornea has too little curvature, so vision condition in which distant objects are usually light entering your eye is not focused correctly. seen clearly, but close ones do • Its effect varies greatly, depending on the not come into proper focus. magnitude of hyperopia, the age of the individual, • Approximately 25% of the the status of the accommodative and general population is hyperopic (a person having hyperopia). convergence system, and the demands placed on the visual system. By Judith Lee and Gretchyn Bailey; reviewed by Dr. Vance Thompson; Flash illustration by Stephen Bagi 1. Cornea is too flap. hyperopia • In theory, hyperopia is the inability to focus and see the close objects clearly, but in practice many young hyperopics can compensate the weakness of their focusing ability by excessive use of the accommodation functions of their eyes. Hyperopia is a refractive error in • But older hyperopics are not as lucky as them. By which parallel rays of light aging, accommodation range diminishes and for 2. Axial is too short. entering the eye reach a focal older hyperopics seeing close objects becomes point behind the plane of the retina, while accommodation an impossible mission. is maintained in a state of relaxation. 1 Amplitude of Accommodation hyperopia Maximum Amplitude= 25-0.4(age) • An emmetropic eye for reading and other near Probable Amplitude= 18.5-.3(age) work, at distance of 16 in (40cm), the required amount of acc.
    [Show full text]
  • Defining Emmetropia and Ametropia As a Function of Ocular Biometry II
    SyntEyes: a Higher Order Statistical Eye Model for Healthy Eyes Jos J. Rozema,*† MSc PhD, Pablo Rodriguez,‡ MSc PhD, Rafael Navarro,‡ MSc PhD, Marie-José Tassignon*†, MD PhD *Dept. of Ophthalmology, Antwerp University Hospital, Edegem, Belgium † Dept. of Medicine and Health Sciences, Antwerp University, Wilrijk, Belgium ‡ICMA, Consejo Superior de Investigaciones Científicas-Universidad de Zaragoza, Facultad de Ciencias, Zaragoza, Spain Abstract Purpose: To present a stochastic eye model that simulates the higher order shape parameters of the eye, as well as their variability and mutual correlations. Methods: The biometry of 312 right eyes of 312 subjects were measured with an autorefractometer, a Scheimpflug camera, an optical biometer and a ray tracing aberrometer. The corneal shape parameters were exported as Zernike coefficients, which were converted into eigenvectors in order to reduce the dimensionality of the model. These remaining 18 parameters were modeled by fitting a sum of two multivariate Gaussians. Based on this fit an unlimited number of synthetic data sets (‘SyntEyes’) can be generated with the same distribution as the original data. After converting the eigenvectors back to the Zernike coefficients, the data may be introduced into ray tracing software. Results: The mean values of nearly all SyntEyes parameters was statistically equal to those of the original data (two one-side t test). The variability of the SyntEyes parameters was the same as for the original data for the most important shape parameters and intraocular distances, but showed significantly lower variability for the higher order shape parameters (F test) due to the eigenvector compression. The same was seen for the correlations between higher order shape parameters.
    [Show full text]
  • Posterior Vitreous Detachment As Observed by Wide-Angle OCT Imaging
    Posterior Vitreous Detachment as Observed by Wide-Angle OCT Imaging Mayuka Tsukahara, OD,1,* Keiko Mori, MD,1 Peter L. Gehlbach, MD, PhD,2 Keisuke Mori, MD, PhD1,3,4,* Purpose: Posterior vitreous detachment (PVD) plays an important role in vitreoretinal interface disorders. Historically, observations of PVD using OCT have been limited to the macular region. The purpose of this study is to image the wide-angle vitreoretinal interface after PVD in normal subjects using montaged OCT images. Design: An observational cross-sectional study. Participants: A total of 144 healthy eyes of 98 normal subjects aged 21 to 95 years (51.4Æ22.0 [mean Æ standard deviation]). Methods: Montaged images of horizontal and vertical OCT scans through the fovea were obtained in each subject. Main Outcome Measures: Montaged OCT images. Results: By using wide-angle OCT, we imaged the vitreoretinal interface from the macula to the periphery. PVD was classified into 5 stages: stage 0, no PVD (2 eyes, both aged 21 years); stage 1, peripheral PVD limited to paramacular to peripheral zones (88 eyes, mean age 38.9Æ16.2 years, mean Æ standard deviation); stage 2, perifoveal PVD extending to the periphery (12 eyes, mean age 67.9Æ8.4 years); stage 3, peripapillary PVD with persistent vitreopapillary adhesion alone (7 eyes, mean age 70.9Æ11.9 years); stage 4, complete PVD (35 eyes, mean age 75.1Æ10.1 years). All stage 1 PVDs (100%) were observed in the paramacular to peripheral region where the vitreous gel adheres directly to the cortical vitreous and retinal surface. After progression to stage 2 PVD, the area of PVD extends posteriorly to the perifovea and anteriorly to the periphery.
    [Show full text]
  • Age-Optimized Vision Correction Laser Blended Vision Modulates Spherical Aberration with Corneal Ablation
    COVER STORY Age-Optimized Vision Correction Laser blended vision modulates spherical aberration with corneal ablation. BY PATRICK VERSACE, MD resbyopia correction has been an elusive goal for laser refractive surgeons. Monovision works well for some patients, but its overall acceptance rate P is approximately 60%.1 Additionally, it carries the intrinsic compromise of reduced binocular fusion, lead- ing to patient dissatisfaction with poor balance, blur, and visual confusion. Several approaches exist for presbyopic laser correc- tion, including multifocal and bifocal corneal optics cre- ated in various patterns. These approaches often provide reasonable near vision under ideal pupil conditions but are generally associated with some compromise in dis- tance vision quality, contrast sensitivity, and patient satis- Figure 1. There is a linear relationship between increases in faction.2 In this article, I describe the use of selective spherical aberration and depth of focus. modulation of spherical aberration as a distinct and alternative approach to presby-LASIK. presence of increased Z(4,0),5 and (3) myopic offset in the Increasing spherical aberration—particularly in a nega- form of mini-monovision. These elements optimize near tive direction—has a direct relationship with increased vision and minimize the compromise of distance vision. depth of focus.3 Adaptive optics modeling has shown a Combining increased Z(4,0) with small amounts of linear relationship between increasing spherical aberra- myopia has been shown to reduce myopic blur. As a result, tion and increased depth of focus for values of Zernike patients maintain better distance vision in the myopic offset coefficient Z(4,0) up to 0.6 µm (Figure 1).4 eye than would be expected.6 We use the term laser blended In practice, it is possible to modulate spherical aberration vision to describe the expanded depth of focus created in through corneal ablation.
    [Show full text]
  • PRESBYOND Laser Blended Vision from ZEISS
    CASE STUDIES CASE OF THE MONTH Treatment of presbyopia with Laser Blended Vision to provide a continuous range of station. The procedure compensates for presbyopia by 95% of emmetropes.1-3 Patient satisfaction rates are also combining micro-monovision with a non-linear aspheric high, although if a patient is unhappy for any reason, the ablation profile that induces spherical aberration to in- treatment can be reversed with spectacle wear or even quality vision crease depth of field, and it has many advantages compa- with another laser procedure. Future enhancement is also Liliana Bányai, Dr. medic, Bányai Laser Centre Leonberg, Germany. red with other surgical approaches for reducing spectacle possible to adjust for progressive presbyopia. dependence in presbyopic patients. CONCLUSION PRESBYOND Laser Blended Vision is more attractive I have been using PRESBYOND Laser Blended Vision than clear lens exchange for many patients because it is successfully in my practice to treat presbyopia in pati- CASE HISTORY ness of 110 µm OU in both eyes were created using the less invasive and avoids the risks of intraocular surgery. ents without cataract for 1.5 years, and it is a good choice A 53-year-old male engineer presented requesting a VisuMax® femtosecond laser (Carl Zeiss Meditec AG, Unlike corneal inlay procedures, PRESBYOND Laser for refractive surgeons who are already performing Fem- solution that would give him spectacle independence Jena, Germany). The ablation was performed using the Blended Vision is suitable for patients with a broad to-LASIK because it requires no new skills. As with any for all of his vision needs.
    [Show full text]
  • Distance Vision, Near Vision and Quality of Life Between Preferred Emmetropia and Residual Myopia in Monofocal Intraocular Lens Implantation - a Comparative Study
    10-Comparative00212_3-PRIMARY.qxd 5/13/21 10:29 PM Page 340 ORIGINAL ARTICLE Distance vision, near vision and quality of life between preferred emmetropia and residual myopia in monofocal intraocular lens implantation - A Comparative study Jaafar Juanarita, MMed 1,2,3 , Abdul Rahman Siti-Khadijah, MBBS 1,2 , Bakiah Shaharuddin, PhD 4, Yaakub Azhany, MMed 1,2 1Department of Ophthalmology and Visual Sciences, School of Medical Sciences, Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia, 2Ophthalmology Clinic, Hospital Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia, 3Hospital Sultanah Bahiyah, Alor Setar, Alor Setar, Kedah, 4Advanced Medical and Dental Institute, Universiti Sains Malaysia, Kepala Batas, Penang, Malaysia unoperated cataracts. 2 Currently, there is no effective ABSTRACT prevention for cataracts, and the only treatment is to remove Introduction: This study was done to evaluate the visual the cloudy lens. 3 acuity and quality of life in predicted emmetropia (EM) and predicted residual myopia (RM) patients following Intraocular lens (IOL) implantation is the commonest phacoemulsification with monofocal intraocular lens practice of visual rehabilitation after cataract surgery. implantation. Monofocal or fixed focal IOLs have only one focus at distance; thus, the placement of a monofocal IOL requires Materials and Methods: This prospective comparative study corrective lenses (spectacles) after surgery for near vision- was conducted in the ophthalmology clinic of the Universiti related tasks. Although no statistical difference was found Sains Malaysia Hospital, Kelantan, Malaysia. Overall, 139 between multifocal (MFIOL) and monofocal IOL with respect patients with senile cataract were randomised into EM and to achieving a post-operative best-corrected visual acuity RM groups. At three months post-operatively, patients were (BCVA) of 6/6, near vision was often found to be better with assessed for distance and near vision, as well as quality of MFIOL.
    [Show full text]
  • Chapter 14 Presbyopia Correction
    Chapter 14 Presbyopia Correction Introduction ....................................................................................208 Nonsurgical Methods for Correction of Presbyopia............209 Surgical Methods for Correction of Presbyopia ...................210 Laser Assisted Presbyopia Corrections25,26 ........................................................216 Conclusion .......................................................................................217 14. Presbyopia Correction Pulak Agarwal, Chirakshi Dhull, Yogita Gupta, and Sudarshan Khokhar Introduction (AP). Thus, it proposes loss of lens capsule elasticity as the main cause of loss of accommodation. Loss of accommodative amplitude due to aging is known as presbyopia. Symptoms include diminution of vision for near Schachar Theory3 sight, headache, asthenopia, and eye strain. Many plausible mechanisms in the form of theories have It proposes that during ciliary contraction, the tension in been proposed for accommodation (Fig. 14.1), equatorial zonular fibers increases, which leads to steepen- ing of anterior lens capsule. With aging, the distance between Helmholtz Theory1,2 ciliary body and the equatorial lens capsule decreases, which causes ineffective tension generation. Most of the scleral- It proposes that when the ciliary body is relaxed, the based interventions are based on this theory. zonules are stretched, which lead to flattening of anterior lens capsule and decrease in the diameter (AP) of the lens. Catenary Theory As opposed to when the ciliary body contracts,
    [Show full text]
  • Previsit Counseling Is Telling BALAMURALI K
    GLOBAL PRACTICE PATTERNS s STRATEGIES FOR CORRECTING PRESBYOPIA | Surgeons share their preferences. Previsit Counseling Is Telling BALAMURALI K. AMBATI, ncreasing maturity (ie, age) comes happens before and after surgery. with reduced focusing adjustment Previsit counseling using Surgiorithm’s MD, PHD, MBA, AND NORALIZ (ie, accommodation). In patients with system has increased the percentage GARCÍA-O’FARRILL, MD cataracts, the restoration of excellent of our patients who elect to undergo visual function can be achieved astigmatic and presbyopia correction Eugene, Oregon Ithrough cataract extraction coupled at the time of cataract surgery from with presbyopia technology. 43% to 53%. This system synergizes educational videos, a lifestyle PREFERENCES AND PROCESSES questionnaire, and information on In the surgical suite. Table 1 shows our available options. preferences for correcting presbyopia. During the preoperative visit, patients preoperative measurements in these Although most presbyopia-correcting learn that they may see rings after eyes and the higher touch-up rate as IOLs can correct only 2.57 D of surgery because of lens-edge effects, will a result. No matter the patient, it is astigmatism, that is not an upper likely have dry eyes for a few months essential to optimize the corneal surface limit because lens technology can be postoperatively, will likely need laser before planning presbyopic cataract combined with intrastromal corneal treatment for scar tissue behind the surgery (Table 2). ring segments, laser arcuate incisions, lens implant in 4 to 12 months after Younger patients without cataracts and limbal relaxing incisions to allow surgery, and may need a free touch-up are offered refractive lens exchange presbyopia correction even in patients for residual astigmatism or refractive (RLE), especially if they have high with 6.00 or 7.00 D of preoperative error.
    [Show full text]
  • Immersion A-Scan Compared with Partial Coherence Interferometry Outcomes Analysis
    Immersion A-scan compared with partial coherence interferometry Outcomes analysis Mark Packer, MD, I. Howard Fine, MD, Richard S. Hoffman, MD, Peggy G. Coffman, COT, Laurie K. Brown, COMT, COE ABSTRACT Purpose: To compare 2 methods of axial length measurement, immersion ultrasonogra- phy and partial coherence interferometry, and to elucidate surgical outcomes based on immersion measurements. Setting: Oregon Eye Institute, Eugene, Oregon, USA. Methods: Axial length measurements in 50 cataractous eyes were obtained by optical biometry (IOLMasterா, Zeiss Humphrey Systems) and immersion ultrasound (Axis II, Quantel Medical), and the results were compared. Intraocular lens (IOL) power calcu- lations in the same eyes after cataract extraction and posterior chamber IOL implanta- tion were evaluated retrospectively based on the postoperative spherical equivalent prediction error. Results: Immersion ultrasonography and partial coherence interferometry measurements correlated in a highly positive manner (correlation coefficient ϭ 0.996). Outcomes analysis demonstrated 92.0% of eyes were within Ϯ0.5 diopter of emmetropia based on immersion axial length measurements. Conclusion: Immersion ultrasonography provided highly accurate axial length measure- ments and permitted highly accurate IOL power calculations. J Cataract Refract Surg 2002; 28:239–242 © 2002 ASCRS and ESCRS xial length measurement remains an indispensable mersion technique.2 Reportedly “user-friendly” and less A technique for intraocular lens (IOL) power calcu- dependent on technician expertise than ultrasound lation. Recently, partial coherence interferometry has methods, noncontact optical biometry is, however, lim- emerged as a new modality for biometry.1 Postoperative ited by dense media, eg, posterior subcapsular cataract. results achieved with this modality have been considered A second limitation of the optical method is the lack of “analogous” to those achieved with the ultrasound im- a lens thickness measurement, a required variable in the Holladay 2 IOL power calculation software, version 2.30.9705.
    [Show full text]
  • Training Eye Instructions
    Training Eye Instructions Using the Direct Ophthalmoscope with the Model Eye The Model Eye uses a single plastic lens in place of the cornea and crystalline lens of the real eye (Fig. 20). The lens is mounted at one end of an open plastic tube into which another tube holding the “retina” is inserted. The model eye also has two different pupil sizes (2, and 4 mm in diameter) that are selected by moving the plastic pupil strip left or right. Taking the pupil strip out completely provides a pupil diameter of 8 mm. pupil strip outside tube convex lens velcro "retina" inside sliding tube Fig. 20. Cross-section of the Model Eye. Assembling the Model Eye Each Model Eye kit contains: Stand Outer tube that mounts on the stand Inner tube that slides into the outer tube Pupil strip 6 black plastic disks 5 images of retinas and 1 mm grid with double-stick tape on back 1 cross hair focus disk Attach the large, outer tube to the stand by pressing the black V-shaped plastic attached to the tube over the clear plastic ball on the stand. Next, insert the smaller-diameter inner tube into the Model Eye. EXPERIMENT 1: Emmetropia In a normal, emmetropic eye, parallel rays of light from a distant object come to focus on the retina (Fig. 21A). Light rays are “reversible”, that is they travel the same path whether going into or out of an optical system. Consequently, if the retina of an emmetropic eye could “light up”, light rays from a point on the retina would exit the eye as parallel rays (Fig.
    [Show full text]
  • Non-Linear Aspheric Ablation Profile for Presbyopic Corneal Treatment Using the Mel80/90 and Crs Master Presbyond Module
    NON-LINEAR ASPHERIC ABLATION PROFILE FOR PRESBYOPIC CORNEAL TREATMENT USING THE MEL80/90 AND CRS MASTER PRESBYOND MODULE Dan Z Reinstein, MD MA(Cantab) FRCSC DABO FRCOphth FEBO1,2,3,4 Timothy J Archer, MA(Oxon) DipCompSci(Cantab)1 Glenn I Carp, MBBCh, FC Ophth (SA)1 1 London Vision Clinic, London, UK 2 Biomedical Science Research Institute, Ulster University, Belfast, UK 3 Department of Ophthalmology, Weill Medical College of Cornell University, NY, USA 4 Centre Hospitalier National d’Ophtalmologie, Paris, France Financial disclosure: Dr Reinstein is a consultant for Carl Zeiss Meditec (Jena, Germany) and has a financial interest in ArcScan Inc (Morrison, CO).. The remaining authors have no proprietary or financial interest in the materials presented herein. Correspondence: Dan Z Reinstein, MD MA(Cantab) FRCSC DABO FRCOphth FEBO, London Vision Clinic, 138 Harley Street, London W1G 7LA, United Kingdom. Tel +44 207 224 1005, Fax +44 207 224 1055, email [email protected] Disclaimer: Not all recommendations, treatment ranges and protocols in this document are officially approved or supported by the products intended use. Where relevant, a comment will be made regarding the official intended use. Also, note that not all products, services or offers are approved or offered in every market and approved labeling and instructions may vary from one country to another. 1 Introduction There has recently been a tremendous increase in interest of surgical presbyopic correction. The effective treatment of presbyopia combined with any refractive
    [Show full text]
  • Profile of Patients with Floaters in Saiful Anwar Hospital Malang
    International Journal of Retina (IJRETINA) 2018, Volume 1, Number 2. P-ISSN. 2614-8684, E-ISSN.2614-8536 PROFILE OF PATIENTS WITH FLOATERS IN SAIFUL ANWAR HOSPITAL MALANG Fenti Kusumawardhani Hidayah, Nadia Artha Dewi, Safaruddin Refa Department of Ophthalmology, Universitas Brawijaya, Malang, Indonesia ABSTRACT Introduction: To report the profile of patients with floaters as a subjective complain in Saiful Anwar Hospital from July 2012 until June 2013. Methods: an observasional descriptive study was conducted, collecting data on gender, age, subjective complain (floaters, flashes and subjective vision reduction), best corrected visual acuity and diagnose from patient’s medical record. Result: 169 patients (215 eyes) were included in this study. Female patients contributed a higher percentage than male with mean of age was 49 years old. The subjective complain was floaters (67%), floater with blurred vision (22%), floater with flashes (6%) and patients with floaters, flashes, and blurred vision was 5%. Myopia was the most common refraction problem. Diagnose recorded from this study were posterior vitreous detachment (PVD) (34%), no abnormalities (13%), PDR (10%), RRD (9%), peripheral retinal degeneration (14%) retinal break (6%), corpus vitreous degeneration (3%), vitreous haemorhage (3%), posterior uveitis (2%) and others (6%). Conclusion: The most common cause of floaters is PVD. Even it is usually a save condition but there are some condition with floater as a subjective complain which is threatening vision, so accurate eye examination from anterior to posterior segment were needed. Keywords: floaters, flashes, blurred vision, vitreoretinal pathology Cite This Article: HIDAYAH, fenti kusumawardhani; DEWI, nadia artha. Profile of Patients with Floaters in Saiful Anwar Hospital Malang.
    [Show full text]